1. Field of the Invention
The present invention relates to ESD protection, and in particular to a mechanism for preventing ESD damage in an electronic device.
2. Description of the Related Art
FIG. 1 is a schematic diagram of signal lines of a conventional liquid crystal display (LCD) panel. The LCD panel comprises a pixel array 12, a plurality of connection areas 10 and a plurality of fan-out signal lines F1 to Fn. Integrated circuits such as a data driver and a scan driver drive the pixel array 12 to display images. As shown in FIG. 1, each connection area 10 has a plurality of pads P1 to Pn arranged sequentially for mounting to the corresponding integrated circuit. The fan-out signal lines F1 to Fn are extend from the pads P1 to Pn respectively. The integrated circuits can provide driving signals, such as scan signals and data signals, to the pixel array 12 through the fan-out signal lines F1 to Fn. Also, the integrated circuits can receive external signals through the fan-out signal lines F1 to Fn.
A thin film transistor (TFT) LCD panel is handled by several machines and operators during the manufacturing process. When a machine or operator generates and transmits electrostatic discharge (ESD) to the TFT LCD panel, signal lines of the TFT LCD panel are open or short, resulting in reduced yield and damage to internal elements. The resulting TFT LCD panel displays abnormal bright or dark lines. TFT LCD panels typically comprise an ESD protection device to prevent ESD from damaging the TFT LCD panel.
Referring to FIG. 1, a conventional method of protecting an LCD panel provides a plurality of ESD protection devices ES1 to EDn disposed corresponding to the fan-out signal lines F1 to Fn. All the ESD protection devices usually have a virtually equal impedance. When ESD occurs in the TFT LCD panel, the ESD protection device of each signal line disposed on outermost side of the connection area 10 has the longest path. Therefore, the electrostatic charges do not disperse and the effectiveness of the protection offered by the ESD protection device is not maintained.